All-terrain scooters are known. See Patmont U.S. Pat. No. 6,012,539. The “all-terrain” scooter disclosed therein is provided with a large central tubular chassis having two central brackets supporting a platform. At the front, the tubular chassis bends upward through a notch in the platform upwardly and above the front wheel to support a steering wheel head tube. At the rear, the tubular frame is offset to one side of the chassis for one-sided cantilevered support of the rear driven wheel, this cantilevered support providing for economic manufacture. From this rear portion of the frame, pivotal and cantilevered mounting of an engine having a protruding shaft with a tire driving surface occurs. Generally, the scooter is driven on enlarged tires with its principal use being off-road, typically over rough terrain.
This scooter has found extensive use in both sporting and off-road patrol functions. Regarding such sporting functions, racing and jumping in both organized and unorganized individual and team competition now regularly occurs. Likewise, in off-road patrol functions, the scooter is typically transported in the trunk of the car or the bed of the truck to the end of a road, lifted from its transported disposition, assembled, and used for transport of a patrolling officer to locations where his car or truck can not take him. In either event, improved all-terrain performance is required. In order for such all-terrain performance to occur, the ability to soften the impact of scooter takeoff and landing from terrain obstacles, such as rocks, potholes, and the like, have been required.
Referring to Martin U.S. Pat. No. 6,338,393, the rear driving wheel is shown mounted to a support bracket pivotal with respect to the rear portion of a scooter. A shock absorber extends between the scooter platform and a point above the scooter platform on the pivoting support bracket. The shock absorber absorbs energy by undergoing compression upon impact of the rear driven wheel of the scooter with the ground.
It is also known to use essentially the same arrangement and have the shock absorber extend between a pivot point underlying the platform and a lower and protruding portion of the rear wheel supporting frame.
Both arrangements have their disadvantages. Where the shock absorber is mounted above the platform, both the mount and the shock absorber are exposed to the foot of the rider. Interference with the rider's firm footing on the platform can occur. Further, the feet of the rider can be knocked out of position on the platform or the feet of the rider can damage the shock absorber. Where the shock absorber is mounted below the platform, the shock absorber is inevitably exposed to the underlying irregular terrain. Where the shock absorber is exposed to the underlying irregular terrain, the inevitable particulate matter impacting the shock absorber can interfere with shock absorber operation and even damage the shock absorber to the point of inoperability.
In both of the above examples, the shock absorber must move relative to the platform and undercarriage of the scooter during shock absorbing motion. This required motion increases the profile required for shock absorber operation relative to the top and/or bottom of the scooter.
Torsion acting shock absorbers are known. In Henschen U.S. Pat. Nos. 5,277,450 and 5,411,287, there is disclosed a torsion axle for use as a shock absorber with trailers. Specifically, square sectioned torsion shafts, square sectioned metal tubes and a plurality of resilient rubber rods acting between the square sectioned torsion shafts and metal tubes are utilized. The resilient rubber rods are confined between the square sectioned metal tubes and the square sectioned metal shafts so as to be compressed by the square sectioned metal shaft when the square sectioned metal shaft rotates relatively to the square sectioned metal tubes. The resilient rubber rods come under compression and torsionally resist rotation of the square sectioned shafts. In a typical application, the metal tubes are attached to the trailer. The torsion shafts are attached to the wheels by an eccentric crank, which eccentric crank is off center with respect to a line extending vertically from the axis of rotation of the wheel vertically upward normal to the trailer. The crank extends outwardly and away from the metal tubes so that the wheels are supported outwardly and away from both the torsion axle and the trailer. When the trailer encounters shock inducing bumps along its path of travel, shock absorbing movement of the crank mounted wheel occurs.
We have a previous shock absorber arrangement designed for a motor powered scooter. In Patmont U.S. Pat. No. 6,668,959 issued Dec. 30, 2003 entitled Scooter with Integral Frame Mounted Shock Absorber, there is disclosed a motor powered scooter for supporting a standing rider that has a front steered wheel, a rear driven wheel, and a platform there between that supports a standing rider on the scooter. The platform is disposed substantially horizontally along a longitudinal axis, and in the preferred embodiment has a main structural tube disposed in supporting relation under the platform. A shock absorber having first and second relatively moving ends for energy absorbing movement is fastened in fixed relation to the underside of the platform with one of the relatively moving ends disposed to and toward the rear driven wheel. In a preferred embodiment, the shock absorber is protectively encased and held within the main structural tube underlying and supporting the platform. A rear frame is provided for supporting the rear driven wheel. This rear frame is connected at a pivot relative to the platform. A linkage has a first connection to the rear frame offset from the pivot. This linkage connects at a second connection at the relatively moving end of the shock absorber. The pivot of the driving wheel supporting frame relative to the platform causes energy absorbing shock absorber movement.
Discovery of Design Criteria
From the standpoint of an economically manufactured and functioning scooter, two design requirements are desirable. First, for the economical manufacture of the scooter, the wheels must be cantilevered with respect to the frame. Traditional fork mounting of either the front or rear axle is to be avoided.
Second, for the functioning of the scooter, it is required that the shock absorber be confined in a completely protected manner while at the same time functioning to dampen the inevitable shock which the scooter undergoes during use. It will be seen that the following disclosed design, enables these design requirements.
Insofar as the prior art does not suggest nor specifically disclose the desirability of these two design requirements, invention is claimed. The reader will understand that determining design requirements as well as meeting those design requirements can constitute invention.